Electroluminescent arrangements using blend systems

ABSTRACT

An electroluminescent arrangement which contains 
     a substrate, 
     an anode, 
     an electroluminescent element, 
     a cathode, 
     and said anode or said cathode is transparent in the visible spectral range and the electroluminescent element is a single layer containing an optionally substituted tris-1,3,5-(aminophenyl)benzene compound (A), a luminescent component B) or a electron-conducting charge-transporting substance.

An electroluminescent (EL) arrangement is characterised in that it emitslight with current flow on the application of an electrical voltage. Intechnology such arrangements have for a long time been known by the term“light diodes” (LEDs =light-emitting diodes). The emission of lighttakes place owing to the fact that positive charges (holes) and negativecharges (electrons) recombine with the emission of light.

Nowadays mainly inorganic semiconductors, such as gallium arsenide, areused in the development of light-emitting components for electronics orphotonics. Display elements in the form of dots can be produced fromsuch substances. Large-surface arrangements are not possible.

Besides the semiconductor light diodes, electroluminescent arrangementsbased on vapour-deposited low-molecular organic compounds are known(U.S. Pat. No. 4,539,507, U.S. Pat. No. 4,769,262, U.S. Pat. No.5,077,142, EP-A 406 762, EP-A 278 758, EP-A 278 757).

Polymers, such as poly(p-phenylenes) and poly(p-phenylenevinylenes)(PPV) are also reported as being electroluminescent polymers: G. Leisinget al., Adv. Mater. 4 (1992) No. 1; Friend et al., J. Chem. Soc., Chem.Commun. 32 (1992); Saito et al., Polymer, 1990, Vol. 31, 1137; Friend etal., Physical Review B, Vol. 42, No. 18, 11670 or WO 90/13148. Furtherexamples of PPV in electroluminescent displays are described in EP-A 443861, WO-A-9203490 and 92003491.

EP-A 0 294 061 introduces an optical modulator based on polyacetylene.

For the production of flexible polymer LEDs, Heeger et al. have proposedsoluble conjugated PPV-derivatives (WO 92/16023).

Polymer blends of varying composition are also known: M Stolka et. al.,Pure 7 Appt. Chem., Vol. 67, No. 1, pp 175-182, 1995; H. Bässler et al.,Adv. Mater. 1995, 7, No. 6, 551; K. Nagaietal., Appl. Phys. Lett. 67(16) 1995, 2281; EP-A 532 798.

The organic EL arrangements generally contain one or more layers oforganic charge-transport compounds. The fundamental structure, in orderof layers, is as follows:

1. carrier, substrate

2. basis electrode

3. hole-injecting layer

4. hole-transporting layer

5. light-emitting layer

6. electron-transporting layer

7. electron-injecting layer

8. top electrodes

9. contacts

10. case, encapsulation.

Layers 3 to 7 constitute the electroluminescent element.

This structure represents the most universal case and can be simplifiedby omitting individual layers, so that one layer assumes severalfunctions. In the simplest case, an EL arrangement consists of twoelectrodes, between which there is an organic layer which fulfils allthe functions, including that of light emission. Such systems aredescribed, for example, in the Application WO 90/13148, based onpoly(p-phenylenevinyls).

Multilayered systems can be built up by vapour-deposition processes,during which the layers are successively applied from the vapour phase,or by casting processes. Casting processes are preferred, because of thehigher processing speeds. Admittedly, the partial solution of an alreadyapplied layer in the course of covering it with the next layer can be adifficulty in certain cases.

The object of the present invention is to provide electroluminescentarrangements which have high luminance and in which the mixture to beapplied can be applied by casting.

It has been found that these requirements are met by electroluminescentarrangements containing the blend system specified below. In thefollowing, the term “zone” is to be regarded as equivalent to “layer”.The present invention accordingly provides electroluminescentarrangements containing a substrate, an anode, an electroluminescentelement and a cathode, wherein at least one of the two electrodes istransparent in the visible spectral range and the electroluminescentelement can contain, in order:

a hole-injecting zone, hole-transporting zone, electroluminescent zone,electron-transporting zone and/or an electron-injecting zone,characterised in that the hole-injecting and/or hole-transporting zoneis an optionally substituted tris-1,3,5-(aminophenyl) benzene compoundA) or a mixture thereof and the electroluminescent element containsoptionally a further functionalised compound selected from among thehole-transporting materials, a luminescent material B) and optionallyelectron-transporting materials, and the hole-injecting andhole-transporting zone can contain one or more further hole-transportingcompounds in addition to component A), at least one zone being present,individual zones can be omitted and the zone(s) present can assume oneor more functions.

A zone can assume several functions; that is to say, a zone can contain,for example, hole-injecting, hole-transporting, electroluminescent,electron-injecting and/or electron-transporting substances.

The electroluminescent element can also contain one or more transparentpolymeric binders C.

The optionally substituted tris-1,3,5-(aminophenyl)benzene compound A)represents an aromatic tertiary amino compound corresponding to thegeneral formula (I)

wherein

R² represents hydrogen, optionally substituted alkyl or halogen,

R³ and R⁴, independently of one another, represent optionallysubstituted C₁-C₁₀-alkyl, alkoxycarbonyl-substituted C₁-C₁₀-alkyl,optionally substituted aryl, optionally substituted aralkyl oroptionally substituted cycloalkyl.

R³ and R⁴, independently of one another, represent preferablyC₁-C₆-alkyl, in particular methyl, ethyl, n- or isopropyl, n-, iso-,sec.- or tert.-butyl, C₁-C₄-alkoxycarbonyl-C₁-C₆-alkyl, such as, forexample, methoxy-, ethoxy-, propoxy-, butoxycarbonyl-C₁-C₄-alkyl; alsophenyl-C₁-C₄-alkyl, naphthyl-C₁-C₄-alkyl, cyclopentyl, cyclohexyl,phenyl or naphthyl, in each case optionally substituted by C₁-C₄-alkyland/or C₁-C₄-alkoxy.

Particularly preferably R³ and R⁴, independently of one another,represent unsubstituted phenyl or naphthyl, or phenyl or naphthyl eachsingly to triply substituted by methyl, ethyl, n-, isopropyl, methoxy,ethoxy, n- and/or isopropoxy.

R² represents preferably hydrogen, C₁-C₆-alkyl, such as, for example,methyl, ethyl, n- or isopropyl, n-, iso-, sec.- or tert.-butyl orchlorine.

Compounds such as these and their preparation are described in U.S. Pat.No. 4,923,774 for use in electrophotography, and the patent just citedis herewith expressly incorporated as part of the present description(“incorporated by reference”). The tris(nitrophenyl) compound can beconverted into the tris(aminophenyl) compound, for example, by generallyknown catalytic hydrogenation, for instance, in the presence of Raneynickel (Houben-Weyl 4/1 C, 14-102, Ullmann (4) 13, 135-148). The aminocompound is reacted with substituted halobenzenes in the generally knownway.

The following compounds, wherein the substitution on the phenyl ring canbe ortho, meta and/or para to the amine nitrogen, are given by way ofexample.

In addition to component A), further hole conductors, for example, inthe form of a mixture with component A), may optionally be used for theconstruction of the electroluminescent element. These may on the onehand be one or more compounds corresponding to formula (I), alsoincluding mixtures of isomers; on the other hand they may also bemixtures of hole-transporting compounds with compounds ofA)—corresponding to the general formula (I)—of different structure.

A list of possible hole-injecting and hole-conducting materials is givenin EP-A 532 798.

In the case of mixtures of component A), the compounds may be used inany proportion between 0 and 100 wt. % (based on the mixture A)). In apreferred embodiment, 1 to 99 wt. % and 99 to 1 wt. %, particularlypreferably 5 to 95 wt. % and 95 to 5 wt. %, are used. In anotherpreferred embodiment, 30 to 70 wt. % and 70 to 30 wt. % are used.

Examples which may be given are:

anthracene compounds, for example, 2,6,9, 10-tetraisopropoxyanthracene;oxadiazole compounds, for example,2,5-bis(4-diethylaminophenyl)-1,3,4-oxadiazole; triphenylaminecompounds, for example,N,N′-diphenyl-N,N′-di(3-methylphenyl)-1,1′-biphenyl-4,4′-diamine;aromatic tertiary amines, for example, N-phenylcarbazole,N-isopropylcarbazole and compounds which can be used inhole-transporting layers, such as are described in the Japanese PatentApplication Offenlegungsnr. 62-264 692; also pyrazoline compounds, forexample,1-phenyl-3-(p-diethylamino-styryl)-5-(p-diethylaminophenyl)-2-pyrazoline;styryl compounds, for example, 9-(p-diethylaminostyryl) anthracene;hydrazone compounds, for example, bis(4-dimethylamino-2-methylphenyl)phenylmethane; stilbene compounds, for example,α-(4-methoxyphenyl)-4-N,N-diphenylamino(4′-methoxy)stilbene; enaminecompounds, for example,1,1-(4,4′-diethoxyphenyl)-N,N-(4,4′-dimethoxyphenyl)-enamine; metalphthalocyanines or nonmetal phthalocyanines and porphyrin compounds.

Triphenylamine compounds and/or aromatic tertiary amines are preferred,the compounds given above as examples being particularly preferred.

The following are examples of materials which have hole-conductingproperties and can be used together with component A) in a mixture.

These and other examples are described in J. Phys. Chem. 1993, 97,6240-6248 and Appl. Phys. Lett., Vol. 66, No. 20, 2679-2681. Binder C)represents polymers and/or copolymers such as, for example,polycarbonates, polyester carbonates, copolymers of styrene such as SANor styrene acrylates, polysulfones, polymers based on monomerscontaining vinyl groups such as, for example, poly(meth)acrylates,polyvinylpyrrolidone, polyvinylcarbazole, vinyl acetate polymers andcopolymers and vinyl alcohol polymers and copolymers, polyolefins,cyclic olefinic copolymers, phenoxy resins et cetera. Mixtures ofdifferent polymers can also be used. The polymeric binders C) havemolecular weights of from 10,000 to 2,000,000 g/mol., are soluble andfilm-forming and are transparent in the visible spectral range. They aredescribed, for example, in Encyclopedia of Polymer Science andEngineering, 2nd Edition, A. Wiley Interscience. They are conventionallyused in a quantity of up to 95 wt.%, preferably up to 80 wt.%, based onthe total weight of A) and B).

Component B) represents a compound corresponding to the general formula(II)

wherein

Me represents a metal,

m is a number from 1 to 3 and

Z independently in both forms represents atoms which complete a nucleuswhich consists of at least 2 condensed rings.

In general monovalent, divalent or trivalent metals which are known toform chelates can be used.

The metal can be a monovalent, divalent or trivalent metal, for example,lithium, sodium, potassium, magnesium, calcium, boron or aluminium.

Z completes a heterocyclic molecular unit which consists of at least twocondensed rings, of which one is an azole or azine ring, and furtheradditional aliphatic or aromatic rings can be bonded to the two fusedrings.

Suitable examples of component B) are the oxine complexes(8-hydroxyquinoline complexes) of Al³⁺, Mg²⁺, In³⁺, Ga³⁺, Zn²⁺, Be²⁺,Li⁺, Ca²⁺, Na⁺ or aluminium tris(5-methyloxine)_(R) and galliumtris(5-chloroquinoline). Complexes with rare earth metals can also beused.

Examples of component B) are

Inq₃, Gaq₃, Znq₂, Beq₂, Mgq₂,

or Al(qa)₃, Ga(qa)₃, In(qa)₃, Zn(qa)₂, Be(qa)₂, Mg(qa)₂, wherein

One or more component B) compounds can be used.

The compounds or the oxine complexes of component B) are generally knownand can be prepared by known methods (cf. for example, U.S. Pat. No.4,769,292).

The electroluminescent arrangements according to the invention arecharacterised by having a light-emitting layer which contains a mixtureof the components A) and B) in optionally a transparent binder C). Herethe weight ratio of A) and B) to one another is variably adjustable.

The percentage by weight of the sum of the percentages by weight of A)and B) in the polymeric binder is in the range of from 0.2 to 98 wt. %,preferably from 2 to 95 wt. %, particularly preferably from 10 to 90 wt.%, most preferably 10 to 85 wt. %.

The weight ratio A:B of components A) and B) is between 0.05 and 20,preferably 0.2 and 10 and particularly preferably between 0.3 and 8, inparticular 0.3 and 7. Components A) and B) may consist either of onecomponent or of a mixture of components of any composition.

To produce the layer, components A), B) and optionally C) are dissolvedin a suitable solvent and by means of casting, knife-coating orspin-coating are applied to a suitable support. This can, for example,be glass or a plastics material provided with a transparent electrode.The plastics material used can be, for example, a sheet ofpolycarbonate, polyester such as polyethylene terephthalate orpolyethylene naphthalate, polysulfone or polyimide.

Suitable transparent electrodes are

a) metal oxides, for example, indium-tin oxide (ITO), tin oxide (NESA),zinc oxide, doped tin oxide, doped zinc oxide, et cetera,

b) semi-transparent metal films, for example, Au, Pt, Ag, Cu, et cetera,

c) conductive polymer films such as polyanilines, polythiophenes, etcetera.

The metal oxide electrodes and the semi-transparent metal filmelectrodes are applied in a thin layer by techniques such as vapourdeposition, sputtering, platinising, et cetera. The conductive polymerfilms are applied from solution by techniques such as spin-coating,casting, knife-coating, et cetera.

The thickness of the transparent electrodes is 3 nm up to about severalμm, preferably 10 mn to 500 nm.

The electroluminescent layer is applied as a thin film directly to thetransparent electrode or to an optionally present charge-transportinglayer. The thickness of the film is 10 to 500 mn, preferably 20 to 400mn, particularly preferably 50 to 250 nm.

An additional charge-transporting layer can be applied to theelectroluminescent layer before a counterelectrode is applied.

A list of suitable charge-transporting intermediate layers, which can behole-conducting and/or electron-conducting materials and can be inpolymeric or low-molecular form, optionally as a blend, is given in EP-A532 798. Specially substituted polythiophenes possessinghole-transporting properties are particularly suitable. They aredescribed, for example, in EP-A 686 662.

The content of low-molecular hole conductors in a polymeric binder isvariable within the range of 2 to 97 wt. %; the content is preferably 5to 95 wt. %, particularly preferably 10 to 90 wt. %, in particular 10 to85 wt. %. The hole-injecting and hole-conducting zones can be depositedby various methods.

Film-forming hole conductors can also be used in pure form (100%). Thehole-injecting or hole-conducting zone may optionally also contain aproportion of an electroluminescent substance.

Blends which consist exclusively of low-molecular compounds can bevapour-deposited; soluble and film-forming blends, which in addition tolow-molecular compounds may also (not necessarily) contain a binder C),can be deposited from a solution, for example, by means of spin-coating,casting, knife-coating.

It is also possible to apply emitting and/or electron-conductingsubstances in a separate layer to the hole-conducting layer containingcomponent A). In this case an emitting substance (“dopant”) can also beadded to the layer containing component A) and in addition anelectron-conducting substance can be applied. An electroluminescentsubstance can also be added to the electron-injecting orelectron-conducting layer.

The content of low-molecular electron conductors in a polymeric binderis variable within the range of 2 to 95 wt. %; the content is preferably5 to 90 wt. %, particularly preferably 10 to 85 wt. %. Film-formingelectron conductors can also be used in pure form (100%).

The counterelectrode is composed of a conductive substance, which can betransparent. Preferred substances are metals, for example, Al, Au, Ag,Mg, In, et cetera, or alloys and oxides of these, which can be appliedby techniques such as vapour-deposition, sputtering, platinising.

The arrangement according to the invention is brought into contact withthe two electrodes by means of two electrical leads (for example, metalwires).

On the application of a direct-current voltage in the range of 0.1 to100 volt, the arrangements emit light having a wavelength of 200 to 2000nm. It displays luminescence in the range of 200 to 2000 nm.

The arrangements according to the invention are suitable for theproduction of units for illumination and for data presentation.

EXAMPLE 1

Electroluminescent arrangement based on a blend system consisting of

A:

B:

 8-hydroxyquinoline aluminium salt (aluminium oxinate)

C: Polyvinylcarbazole (Luvican EP, BASF AG, Ludwigshafen, Germany)

A 1% solution consisting of 1 part by weight A, 1 part by weight B and 4parts by weight C in dichloroethane is spread out on a glass platecoated with ITO (Baltracon 255 from the firm Balzers) by means of acommercial spin-coater at a rate of rotation of 400/min.

The layer thickness is 100 nm.

As counterelectrode, Mg/Ag in the ratio of 10:1 is applied by thermalcodeposition.

After contacting and application of an electrical field, from about 7 Vthe arrangement shows visually detectable electroluminescence in thegreen spectral range. The luminous intensity is 355 cd/m² at a currentof 19 mA/cm² and a voltage of 16 V.

EXAMPLE 2

Electroluminescent arrangement based on a blend system consisting of:

A) 1 part by weight of the following compound:

B) 1 part by weight Alq₃

C) 4 parts by weight polyvinylcarbazole (Luvican EP, BASF AG,Ludwigshafen, Germany).

Layer production and contacting are carried out as in Example 1. Theluminous intensity at an applied voltage of 16 V and a current of 22.6mA/cm² is 455 cd/M².

EXAMPLE 3

Electroluminescent arrangement based on a blend system consisting of:

A) 1 part by weight of the following compound:

B) 1 part by weight Alq₃

C) 4 parts by weight polyvinylcarbazole (Luvican EP, BASF AG,Ludwigshafen, Germany).

Layer production and contacting are carried out as in Example 1. Theluminous intensity at an applied voltage of 20 V and a current of 18.7mA/cm² is 310 cd/m².

EXAMPLE 4

Electroluminescent arrangement based on a blend system consisting of:

A) 1 part by weight of the following compound:

B) 1 part by weight Alq3

C) 4 parts by weight polyvinylcarbazole (Luvican EP, BASF AG,Ludwigshafen, Germany).

Layer production and contacting are carried out as in Example 1. Theluminous intensity at an applied voltage of 15 V and a current of 17.6mA/cm² is 250 cd/m².

EXAMPLE 5

Electroluminescent arrangement containing a hole-conducting layer basedon

A) a mixture of the hole conductors (weight ratio 1:1)

B) an electron-conducting or emitting layer based on

 8-hydroxyquinoline aluminium salt (aluminium oxinate) and

C) polystyrene (Aldrich, 89555 Steinheim, Germany, product number:18,242-7)

A 1% solution, consisting of 1 part by weight A, 1 part by weight B and1 part by weight C in dichloroethane is spread out on a glass platecoated with ITO (Baltracon 255 from the firm Balzers) by means of acommercial spin-coater at a rate of rotation of 800/min. Anelectron-conducting or emitting layer, consisting of Alq₃, isvapour-deposited at 10⁻⁶ mbar onto this hole-conducting layer. The layerthickness is approximately 60 nm.

As counterelectrode, an Mg/Ag alloy in the ratio of 10:1 is applied bythermal codeposition. The system emits green light. The diode emitsgreen light at a voltage of 3 V and above.

EXAMPLE 6

Electroluminescent arrangement based on component A:

A 1.5% solution of A) in chloroform is spread out on a glass platecoated with ITO (Baltracon 255 from the firm Balzers) by means of acommercial spin-coater at a rate of rotation of 1000/min. The layerthickness is 120 nm.

As counterelectrode, Al is applied by thermal vaporisation.

After contacting and application of an electrical field, from 8 Velectroluminescence can be detected by means of an Si photodiode. At avoltage of 20 V, a current of 25 mA/cm² flows and the luminance is 2cd/m². The colour of the electroluminescence is blue.

What is claimed is:
 1. An electroluminescent arrangement which comprisesa substrate, an anode, an electroluminescent element and a cathode, andsaid anode or said cathode is transparent in the visible spectral rangeand the electroluminescent element is a single layer consistingessentially of an optionally substituted tris-1,3,5-(aminophenyl)benzenecompound A) or mixtures thereof, with optionally one or morehole-transporting compounds which have a structure different fromformula (I),

wherein R² represents hydrogen, optionally substituted alkyl or halogen,R³ and R⁴, independently of one another, represent optionallysubstituted C₁-C₁₀-alkyl, alkoxycarbonyl-substituted C₁-C₁₀-alkyl,optionally substituted aryl, optionally substituted aralkyl oroptionally substituted cycloalkyl, a luminescent component B) which is acompound corresponding to formula (II):

and wherein Me represents a metal, m is a number from 1 to 3, n is 1,2or 3 and z independently in both forms represents atoms which complete anucleus which contains at least 2 condensed rings; or mixtures thereof;and optionally a transparent polymeric binder C).
 2. Theelectroluminescent arrangement according to claim 1, wherein thecompound A) is an aromatic tertiary amino compound corresponding to thegeneral formula (I)

wherein R² represents hydrogen, optionally substituted alkyl or halogen,R³ and R⁴, independently of one another, represent optionallysubstituted C₁-C₁₀-alkyl, alkoxycarbonyl-substituted C₁-C₁₀-alkyl,optionally substituted aryl, optionally substituted aralkyl oroptionally substituted cycloalkyl.
 3. The electroluminescent arrangementaccording to claim 2, wherein in formula (I) R² represents hydrogen orC₁-C₆-alkyl, R³ and R⁴, independently of one another, representC₁-C₆-alkyl, C₁-C₄-alkoxycarbonyl-C₁-C₆-alkyl, phenyl, naphthyl,phenyl-C₁-C₄-alkyl, naphthyl-C₁-C₄-alkyl, cyclopentyl or cyclohexyl, ineach case optionally substituted by C₁-C₄-alkyl, C₁-C₄-alkoxy or bothC₁-C₄-alkyl and C₁-C₄-alkoxy.
 4. Electroluminescent arrangementaccording to claim 1, wherein the compound A) is selected from thefollowing compounds:


5. The electroluminescent arrangement according to claim 1, whereincomponent B) is selected from oxine complexes of Al³⁺, Mg²⁺, In³⁺, Li²⁺,Ca²⁺, Na⁺; aluminum tris(5-methyloxine); gallium tris(5-chloroquinoline)and rare earth metal complexes.
 6. The electroluminescent arrangementaccording to claim 1, wherein the percentage by weight of the sum of thepercentages by weight of A) and B) in the polymeric binder is in therange of from 0.2 to 98 wt. % (based on 100 wt. % of A)+B)+C)) and theweight ratio A):B) of components A) and B) is between 0.05 and
 20. 7.The electroluminescent arrangement according to claim 1 wherein thetransparent polymeric binder C) is selected from a group consisting ofpolycarbonates, polyester carbonates, copolymers of styrene, styreneacrylates, polysulfones, polymers based on monomers containing vinylgroups, polyolefins, cyclic olefinic copolymers and phenoxy resins. 8.An illumination which comprises electroluminescent arrangement accordingto claim
 1. 9. A background illumination component which comprises anelectroluminescent arrangement according to claim
 1. 10. Anelectroluminescent arrangement which comprises a substrate, an anode, anelectroluminescent element and a cathode, and said anode or said cathodeis transparent in the visible spectral range and the electroluminescentelement is a single layer containing an optionally substitutedtris-1,3,5-(aminophenyl)benzene compound A), 8-hydroxyquinoline aluminumsalt and polyvinylcarbazole.
 11. The electroluminescent arrangementaccording to claim 10, wherein the electroluminescent element furthercontains a transparent polymeric binder C).
 12. The electroluminescentarrangement according to claim 11, wherein the transparent polymericbinder C) is selected from a group consisting of polycarbonates,polyester carbonates, copolymers of styrene, styrene acrylates,polysulfones, polymers based on monomers containing vinyl groups,polyolefins, cyclic olefinic copolymers and phenoxy resins.
 13. Theelectroluminescent arrangement according to claim 10, wherein thecompound A) is selected from the following compounds:


14. The electroluminescent arrangement according to claim 10, whereinthe compound A) is an aromatic tertiary amino compound corresponding tothe general formula (I)

wherein R² represents hydrogen, optionally substituted alkyl or halogen,R³ and R⁴, independently of one another, represent optionallysubstituted C₁-C₁₀-alkyl, alkoxycarbonyl-substituted C₁-C₁₀-alkyl,optionally substituted aryl, optionally substituted aralkyl oroptionally substituted cycloalkyl.
 15. The electroluminescentarrangement according to claim 14, wherein said electroluminescentelement further comprises one or more hole-transporting compounds whichhave a structure different from formula (I).
 16. The electroluminescentarrangement according to claim 14 wherein in formula (I) R² representshydrogen or C₁-C₆-alkyl, R³ and R⁴, independently of one another,represent C₁-C₆-alkyl, C₁-C₄-alkoxycarbonyl-C₁-C₆-alkyl, phenyl,naphthyl, phenyl-C₁-C₄-alkyl, naphthyl-C₁-C₄-alkyl, cyclopentyl orcyclohexyl, in each case optionally substituted by C₁-C₄-alkyl,C₁-C₄-alkoxy or both C₁-C₄-alkyl and C₁-C₄-alkoxy.
 17. An illuminationwhich comprises electroluminescent arrangement according to claim 10.18. A background illumination component which comprises anelectroluminescent arrangement according to claim 10.